In general, this invention relates to a piston and to a method of forming the piston. More specifically, but not exclusively, this invention is directed to a temperature-resistant piston head formed of a high temperature-resistant material and to a method of forming the temperature-resistant piston head.
Typical piston heads are formed of a single material that is selected to provide the requisite mechanical strength at the temperatures normally experienced in internal combustion engines. These materials are typically forged or cast steel alloys, which are subsequently heat-treated to improve their high temperature and temper resistance.
One prior art piston head includes a piston crown section and a connecting rod section. A friction weld joins the two sections into an assembled piston head. The two sections are formed of the same forged or cast steel alloy material to facilitate friction welding and subsequent heat treatment.
To improve performance, it is becoming increasingly desirable to operate internal combustion engines at higher temperatures. This desire is especially prominent in relation to larger diesel engines used in electrical power generation applications. Unfortunately, existing pistons tend to more readily oxidize, particularly at the combustion bowl rim, which typically is subjected to the highest operating temperature. The combustion bowl rim, and the piston head in general, may suffer from a loss of hardness if exposed to more extreme temperatures. As a result, piston head failure may become more frequent.
Thus, there is a need to provide pistons capable of withstanding the extreme thermal and mechanical loading likely to result from new, higher performance engines. The present invention addresses these needs.